I haven't priced HRD's on eBay, but I did some research on the Blues Junior before buying one there. The standard model BJr with no additional bells & whistles, used and in good to excellent condition, should typically sell for somewhere in the range of $275 - $350. Additional features (e.g. foot pedal or amp cover) will raise the price, as will uncommonly good ("mint") condition. Also, the blond tolex version sells for a bit more than the black one, since they're much less common (though functionally identical to the black).
What really bumps up the price are things like preinstalled "BillM" or other performance-enhancement modifications, or the amp being the more expensive "lacquered Tweed NOS" version. The latter sells new for $530 vs. $450 for the standard BJr here in the US, and comes with an upgraded Jensen speaker. That is the only functional difference between the two; otherwise, they differ only in the fancier finish on the Tweed NOS version. These sell on eBay for a typical price premium of $100 - $150, which is W-A-A-A-Y overpriced, IMO. You can buy the upgraded Jensen speaker for about $62 + shipping, so the rest of the premium is for the fancy lacquered tweed tolex! And there's a "reliced" tweed NOS version that sells for even more.... :whatever:
The prices I saw on the "pre-modded" Blues Juniors were ridiculously high, as well. I would recommend against these amps, not only because of the large price premium, but also because you generally have no idea how competently such mods were done. It's easy to do a "hack job", if you don't know what you're doing. If you want a modded BJr and don't have the knowledge & ability to do the work yourself (Mandatory Tube Amp Warning: You can KILL yourself with the high DC voltages inside a tube amp, even when they're unplugged! ), buy a stock amp and bring it to a professional.